1 // Copyright ©2015 The Gonum Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
7 import "gonum.org/v1/gonum/blas/blas64"
9 // Dlaswp swaps the rows k1 to k2 of a rectangular matrix A according to the
10 // indices in ipiv so that row k is swapped with ipiv[k].
12 // n is the number of columns of A and incX is the increment for ipiv. If incX
13 // is 1, the swaps are applied from k1 to k2. If incX is -1, the swaps are
14 // applied in reverse order from k2 to k1. For other values of incX Dlaswp will
15 // panic. ipiv must have length k2+1, otherwise Dlaswp will panic.
17 // The indices k1, k2, and the elements of ipiv are zero-based.
19 // Dlaswp is an internal routine. It is exported for testing purposes.
20 func (impl Implementation) Dlaswp(n int, a []float64, lda int, k1, k2 int, ipiv []int, incX int) {
26 case k1 < 0 || k2 < k1:
28 case len(ipiv) != k2+1:
30 case incX != 1 && incX != -1:
37 bi := blas64.Implementation()
39 for k := k1; k <= k2; k++ {
40 bi.Dswap(n, a[k*lda:], 1, a[ipiv[k]*lda:], 1)
44 for k := k2; k >= k1; k-- {
45 bi.Dswap(n, a[k*lda:], 1, a[ipiv[k]*lda:], 1)